Solvation Sheath Reorganization by Alkyl Chain Tuning Promises Lean-Electrolyte Li–S Batteries

Abstract

Sparsely solvating electrolyte (SSE), which can achieve a quasi-solid-phase sulfur reaction path, stands out as a promising strategy to alleviate the dependence on electrolyte usage and construct lean-electrolyte lithium–sulfur (Li–S) batteries. Nonetheless, its formation relies upon a high dosage of salt and diluent, thereby leading to increased electrolyte cost. To this end, we herein customize a localized SSE (LSSE) featuring a low ratio of salt-to-solvent and diluent-to-solvent through alkyl chain tuning. A multimodal 2D nuclear magnetic resonance technique is developed to unveil the Li-ion solvation sheath reorganization, which is crucial for studying the coordination and dynamics in liquid electrolytes. LSSE affords an anion-derived solid electrolyte interface and effective restriction of the shuttling effect; hence, our Li–S batteries can sustain a steady operation under 4 μL mg_S^–1 and 3 mg cm^–2. Our work opens a new avenue for advancing SSE design in the pursuit of pragmatic lean-electrolyte Li–S batteries.